This research aims to define the structure, function, and biosynthesis of polyadenylate sequences that have been found to exist in large amounts in the pulse-labelled RNA of Bacillus brevis. Such sequences have been long recognized in mRNA of eukaryotic cells, but on account of the much greater complexity of RNA metabolism in these organisms, their function has been difficult to characterize. Using the simpler bacterial system, we will characterize the rate of synthesis and degradation of poly(A)-RNA and compare its properties with unadenylated RNA in terms of its ability to direct protein synthesis, to hybridize with specific DNA sequences, and its relative amounts during vegetative growth and sporulation, in the hope that a functional difference between the two types of RNA will emerge. The mode of synthesis of poly(A)RNA will be characterized in cells made selectively permeable to small molecules by treatment with toluene, and attempts will be made to characterize an enzyme responsible for the synthesis of poly(A) sequences.